1. Field of the Invention
This invention relates to car washing apparatus having a rotary brush, and more particularly, to an adjustable tensioning device mounted to a wraparound brushing mechanism selectably to vary the magnitude and location of maximum engagement force exerted by the brush on the exterior of a car during a washing operation.
2. Description of Related Prior Art
Wraparound brushing mechanisms of the type disclosed in U.S. Pat. No. 3,350,733 accomplish a car washing operation with the use of a vertically disposed rotary brush suspended at the end of a pivotable mounting structure that is adapted to urge the brush against the front end, side, and rear end of a car advancing along a conveyor track. The wraparound mechanism includes an inner arm pivotally mounted to a stationary support structure about a fixed axis and an outer arm pivotally mounted intermediate its ends to the outer end of the inner arm. The rotary brush is suspended from the free end of the outer arm.
Initially, the biasing mechanism for a wraparound brush include only an extensible spring disposed between the support structure and the inner end of the pivotable outer arm carrying the rotary brush. The extensible spring applied the force to urge the brush against the exterior of the car. Since the force of a spring increases in proportion to its extension, the wraparound brushing mechanism pivotally moving to follow the contour of the car being washed stretches and shortens the length of the spring, thereby applying an uncontrolled, nonuniform urging force to the brush against the surface of the car.
Undesirable effects of such uncontrolled, nonuniform urging forces arise when the force increases to an amount sufficient to cause the rotary brush to inflict damage to objects mounted on the exterior of the car and to impede the following action of the wraparound mechanism as the brush travels along the exterior of the car.
To overcome this disadvantage, a biasing mechanism having a counterweight system, such as that disclosed in U.S. Pat. No. 3,704,476, was included in the wraparound brushing mechanism to provide a more uniform force exerted by the brush against the surface of the car.
This particular counterweight system comprises a counterweight suspended from a cable which is routed along a system of pulleys mounted to the support structure. The other end of the cable is connected to the end of the spring previously attached to the support structure. Under the operating principles of this biasing mechanism, the initial engagement of the car with the rotary brush causes the spring increasingly to expand until a spring force sufficient to raise the counterweight is attained. As the brush moves along the exterior of the car, the counterweight moves in accordance with orientation of the wraparound mechanism to apply a constant force thereto, thereby to maintain a uniform engagement force by the brush against the surface of the car.
In recent years the growth in demand for use of a car wash facility, especially during peak hours, has necessitated an increase in conveyor speed to process more quickly the cars advancing through the car wash installation. Improvements in the design of brush components and materials have afforded greater scrubbing efficiency to keep pace with the required higher linear speed of the brush along the exterior surface of the car. The speed of brush rotation also has been increased to ensure a thorough cleaning operation.
An increase in conveyor and brush rotation speeds has introduced anomalies in controlling the wraparound brushing mechanism with respect to maintaining contact of the brush against the surface of the car as it advances along the conveyor track. In particular, the direction of brush rotation is selected to assist the linear movement of the brush outward toward the side and rearward toward the end portions of the car. The increased linear and rotational brush speeds tend to propel the brush away from the car as it turns about the front and rear corners thereof. Thus, for a short time the brush loses contact with the side surface of the car, thereby leaving a portion unscrubbed. In addition, in car wash establishments operating at relatively high conveyor and brush rotation speeds, it has been observed that the brush will impact the side of the car precisely at the point where the side view mirror is mounted. This unfortunate event upon occasion has resulted in the detachment of the side view mirror.
A critical parameter affected by an increase in conveyor and brush rotation speeds is the amount of engagement force applied to the brush against the surface of the car when the brush begins to turn about the rear corner of the car to scrub the rear end portion thereof. A particularly large amount of urging force must be applied to the brush during this event to maintain sufficient traction against the surface of the car, otherwise the brush rotating at high speeds will tend to push away from the car as it quickly recedes from the path of brush movement.
It has also been observed that the tendency of the brush to lose contact with or ineffectively scrub a portion of the car under the conditions of increased conveyor and brush rotation speeds is enhanced by misalignment of the wraparound mechanism. Such misalignment can be caused by either improper maintenance or general deterioration stemming from the recurrent impact of the brush with the cars during the initial phase of the washing sequence. In addition, the downwardly sloping floor accommodating the drainage system makes the hitherto less critical alignment procedure of the brushing mechanism difficult to accomplish. Thus, the effect of an intensified pace of processing cars through a washing installation has been to raise the sensitivity of the brushing mechanism to deviations from the specified distribution of scrubbing forces, especially at the aforementioned stages of the washing sequence.
Increasing the mass of the counterweight is not a feasible solution to these problems because such would result in exerting a uniformly distributed, excessive brush force to portions of the car where it is neither necessary nor desirable.
An important object of this invention, therefore, is to provide a tensioning device for a wraparound brushing mechanism to maintain brush contact with a car during the washing thereof during high speed conditions for both the conveyor and rotary brush.
Another important object of this invention is to provide an adjustable tensioning device to apply a controlled, nonuniform force to a brush in engagement with the surface of a car.
A further important object of this invention is to provide an adjustable tensioning device adapted to vary the point of maximum influence of the biasing mechanism to fix the location on the car for application of maximum brush engagement force.
Still another important object of this invention is to provide an adjustable tensioning device to vary the overall amount of leverage applied to the rotary brush contacting the surface of the car.
Another object of this invention is to provide an adjustable tensioning device to compensate for misalignment of the wraparound brushing mechanism to realign the forces necessary for maintaining continuous brush contact with the car.
Another object of this invention is to provide an adjustable tensioning retrofit device that is easily adaptable to an earlier installed wraparound brushing mechanism.